Network Working Group R. Bless
Request for Comments: 3662 Univ. of Karlsruhe
Category: Informational K. Nichols
Consultant
K. Wehrle
Univ. of Tuebingen/ICSI
December 2003
A Lower Effort Per-Domain Behavior (PDB) for Differentiated Services
Status of this Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract
This document proposes a differentiated services per-domain behavior
(PDB) whose traffic may be "starved" (although starvation is not
strictly required) in a properly functioning network. This is in
contrast to the Internet's "best-effort" or "normal Internet traffic"
model, where prolonged starvation indicates network problems. In
this sense, the proposed PDB's traffic is forwarded with a "lower"
priority than the normal "best-effort" Internet traffic, thus the PDB
is called "Lower Effort" (LE). Use of this PDB permits a network
operator to strictly limit the effect of its traffic on "best-
effort"/"normal" or all other Internet traffic. This document gives
some example uses, but does not propose constraining the PDB's use to
any particular type of traffic.
1. Description of the Lower Effort PDB
This document proposes a differentiated services per-domain behavior
[RFC3086] called "Lower Effort" (LE) which is intended for traffic of
sufficiently low value (where "value" may be interpreted in any
useful way by the network operator), in which all other traffic takes
precedence over LE traffic in consumption of network link bandwidth.
One possible interpretation of "low value" traffic is its low
priority in time, which does not necessarily imply that it is
generally of minor importance. From this viewpoint, it can be
Bless, et al. Informational [Page 1]RFC 3662 Lower Effort PDB December 2003
considered as a network equivalent to a background priority for
processes in an operating system. There may or may not be memory
(buffer) resources allocated for this type of traffic.
Some networks carry traffic for which delivery is considered
optional; that is, packets of this type of traffic ought to consume
network resources only when no other traffic is present.
Alternatively, the effect of this type of traffic on all other
network traffic is strictly limited. This is distinct from "best-
effort" (BE) traffic since the network makes no commitment to deliver
LE packets. In contrast, BE traffic receives an implied "good faith"
commitment of at least some available network resources. This
document proposes a Lower Effort Differentiated Services per-domain
behavior (LE PDB) [RFC3086] for handling this "optional" traffic in a
differentiated services domain.
There is no intrinsic reason to limit the applicability of the LE PDB
to any particular application or type of traffic. It is intended as
an additional tool for administrators in engineering networks.
Note: where not otherwise defined, terminology used in this document
is defined as in [RFC2474].
2. Applicability
A Lower Effort (LE) PDB is for sending extremely non-critical traffic
across a DS domain or DS region. There should be an expectation that
packets of the LE PDB may be delayed or dropped when other traffic is
present. Use of the LE PDB might assist a network operator in moving
certain kinds of traffic or users to off-peak times. Alternatively,
or in addition, packets can be designated for the LE PDB when the
goal is to protect all other packet traffic from competition with the
LE aggregate, while not completely banning LE traffic from the
network. An LE PDB should not be used for a customer's "normal
internet" traffic, nor should packets be "downgraded" to the LE PDB
for use as a substitute for dropping packets that ought to simply be
dropped as unauthorized. The LE PDB is expected to be applicable to
networks that have some unused capacity at some times of day.
This is a PDB that allows networks to protect themselves from
selected types of traffic rather than giving a selected traffic
aggregate preferential treatment. Moreover, it may also exploit all
unused resources from other PDBs.
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